Their web site does not have a list of instructions but since most watches are very similar, with a little esperimenting, you should be able to sort it out.
Try the following;-
Press the "mode" button on th eupper left and this will take you into the setting menu. Keep pressing the mode button and you should arrive at a point where the screen displays the hour that the watch is at present set at. Experiment with the buttons on the right to find the setting button which changes the hours.
When you have set the hours, press the mode button again and you should see the minutes. Using the setting button to adjust the minutes.
Press the mode button again until the new time is displayed.
If you have no success, then go to their web site
http://www.cardinalwatch.com/ and go to the "contact us" and ask them for a set of instructions.
Have patience!
Good luck!